1. Field of the Invention
The present invention relates to an ink-jet printer in which a plurality of recording heads are temperature controlled at an optimum recording temperature to obtain a good image quality in a low-temperature environment, and to a temperature control method of the plurality of recording heads.
2. Description of the Related Art
Heretofore, a recording head has a sub-heater, a driving signal applied to the sub-heater is pulse width modulated (PWM) in accordance with a detected present temperature of the recording head to increase the recording head temperature to an optimum temperature for printing.
For example, when making recording using four recording heads in a low-temperature environment, sub-heaters of all the recording heads are necessary to be applied with voltages by the PWM control.
For example, when a sub-heater of each recording head is applied with a voltage at a 25% duty with respect to the driving period, since the heating power supply voltage VH is applied simultaneously to all the recording heads (only area A of FIG. 8), the heating power supply voltage VH for increasing the temperature of the recording heads in area A is dropped, so that the temperature does not reach the target or desired temperature resulting in a degraded recording or the like.